Application of a 3D tractor-driving simulator for slip estimation-based path-tracking control of auto-guided tillage operation

Abstract

Successful adoption of auto-steering agricultural vehicles in Korean paddy fields depends on the ability to accurately follow a full path, including straight and curved paths for agricultural tasks and headland turning in each row, in the presence of sliding caused by wet ground conditions in relatively small fields. To improve the performance of an autonomous tillage tractor originally developed in our previous study, this article describes a simulation study, conducted using a 3D computer simulator, that accounts for the slippery motion of a virtual tractor on ground with varying adherence properties, In addition, this study performed field evaluation of an auto-guided tillage tractor equipped with a slip estimation-based path-tracking algorithm that is robust to slippage in paddy fields. The test platform was built with a 60-kW tractor equipped with an RTK-GPS (real-time kinematic-global positioning system) and IMU (inertial measurement unit) system, a navigation controller that could estimate the sideslips of the tractor in real-time, and a three-point hitch dynamometer that could measure tillage drafts. The results of the computer simulation confirmed that the slip estimation-based path-tracking algorithm was superior in guiding the tractor along curved paths on the ground with relatively low coefficients of cornering stiffness by reducing the lateral deviations as compared with those obtained with the conventional look-ahead distance method. In field tests run in an arable field, the autonomous tillage tractor equipped with the slip observer algorithm demonstrated improved performance as compared to the previously developed system by reducing the RMSE (root mean square error) for lateral deviation on curved paths from 29 cm to 15 cm. (C) 2018 IAgrE. Published by Elsevier Ltd. All rights reserved.